The present invention relates to an orthodontic bracket, and in particular an orthodontic bracket where a liner is provided in an archwire slot for receiving an archwire so as to increase rupture strength and sliding property of the archwire slot.
For example, among conventional orthodontic brackets, some comprise a plate-shaped base to be secured to the surface of the teeth, a bracket main body furnished on the base at its one side, an archwire slot formed in the bracket main body, and a liner of U-shape in cross section provided along the archwire slot.
The liner is provided in the archwire slot, thereby enabling to reinforce the archwire slot. For correcting a bad row of teeth, a square or rectangular archwire is received within the liner following a sequence of the archwire, so that the archwire slot can be avoided from bending with the liner when applying torque to the archwire slot through the square or rectangular archwire.
Sliding property within the archwire slot can be improved by the liner. In case a bracket main body is composed of ceramics or plastic, the sliding with the archwire is inferior as known, and for example, if a metal-made liner is furnished, friction with the archwire can be reduced.
One example is known as a liner shown in FIG. 8. The liner 100 is defined with respective openings 102 in both side walls 101, and when the liner 100 is inserted in the orthodontic bracket, plastic flows into each of the openings 102 to prevent the liner 100 from slipping out of the orthodontic bracket.
Another example is known as a liner shown in FIG. 9. The liner 105 is formed with projections 107 in both side walls 106 toward a mesiodistal direction, and when the liner 105 is inserted in the orthodontic bracket, plastic flows into each of under-cut portions 108 under the projections 107 to prevent the liner 105 from slipping out of the orthodontic bracket.
A further example is known as a liner shown in FIG. 10. The liner 110 is provided with flanges 111 bent at right angle at mesiodistal ends, and the flanges 111 prevent the liner 110 from slipping out of the orthodontic bracket.
A still further example is known as a liner shown in FIG. 11. The liner 115 extends white-coated wings 116 to the inside of tiewings of the orthodontic bracket, and the wings 116 prevent the liner 115 from slipping out of the orthodontic bracket.
A yet further example is known as a liner shown in FIG. 12. The liner 120 is formed with bulky parts 121, and when the liner 120 is inserted in the orthodontic bracket, the respective bulky parts 121 are buried in the plastic to prevent the liner 120 from slipping out of the orthodontic bracket.
However, as to the liner 100 shown in FIG. 8, if the plastic too much projects from the respective openings 102, the projected plastic obstructs the archwire sliding and causes delay in curing for the correction of dentition. Therefore, it is necessary to heighten precision when the liner 100 is inserted into the orthodontic bracket, and this hampers the cost-down.
Further, as to the liner 105 shown in FIG. 9, if the plastic too much goes out from the respective under-cut parts 108, the projected plastic obstructs the archwire sliding and consequently causes delays of movement of the teeth. Therefore, similarly to the liner 100 of FIG. 8, it is necessary to heighten precision when the liner 105 is inserted into the orthodontic bracket, and this hampers the cost-down.
In addition, the liner 110 shown in FIG. 10 is provided with the respective flanges 111 bent at the mesiodistal ends, and when the liner 110 is inserted into the orthodontic bracket, the flanges 111 project from the mesiodistal ends of the orthodontic bracket, so that there is a room for improving an external appearance.
In the liner shown in FIG. 11, even if the wings 116 is white-coated but as it extends to the inside of the transparent plastic tiewings, a room is still left for improving the external appearance.
Besides, since the liner 120 shown in FIG. 12 is formed with the bulky parts 121, it is complicated in shape, and it is difficult to maintain the liner precise, and this disturbs the cost-down.